com.itemanalysis.psychometrics.cmh

Class CochranMantelHaenszel

java.lang.Object

com.itemanalysis.psychometrics.cmh.CochranMantelHaenszel

public class CochranMantelHaenszel
extends java.lang.Object

See the article below for details: Zwick, R., & Thayer, D. T. (1996). Evaluating the magnitude of differential item functioning in polytomous items. Journal of Educational and Behavioral Statistics, 21, 187-201.

Author:

J. Patrick Meyer

Constructor Summary

Constructors

Constructor and Description
CochranMantelHaenszel(java.lang.String focalCode, java.lang.String referenceCode, VariableAttributes groupVariable, VariableAttributes itemVariable, boolean etsDelta)

Method Summary

Modifier and Type	Method and Description
double	cochranMantelHaenszel()
double	commonOddsRatio() Computed only for the first two rows and first two columns in each strata
double[]	commonOddsRatioConfidenceInterval(double commonOddsRatio) Computes 95% confidence interval for the common odds ratio.
double	commonOddsRatioVariance()
java.lang.String	etsBinayClassification(double cochranMantelHaenszel, double pvalue, double commonOddsRatio)
double	etsDelta(double commonOddsRatio)
double	focalTotalSize()
java.lang.String	getDatabaseString() This method provides the results in a form that can be inserted into a database table.
double	getEffectSize()
double[]	getEffectSizeConfidenceInterval()
java.lang.String	getETSDifClassification()
double	getPValue()
int	getSampleSize()
VariableName	getVariableName()
void	increment(double strataScore, java.lang.String groupValue, double itemScore)
double	pF() Computes the standardized mean difference (SMD).
java.lang.String	printHeader()
java.lang.String	printTables() From 1999 South Carolina PACT Technical Documentation
double[]	smdConfidenceInterval(double standardizedMeanDifference) Computes 95% confidence interval for the standardized mean difference.
java.lang.String	smdDifClass()
java.lang.String	toString()
double	varianceSMD() Compute variance of the standardized mean difference (SMD).
double	zSMD() Returns a Z test of the SMD statistic, Z_H(SMD) on page 194 of Zwick and Thayer (1996).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CochranMantelHaenszel

public CochranMantelHaenszel(java.lang.String focalCode,
                             java.lang.String referenceCode,
                             VariableAttributes groupVariable,
                             VariableAttributes itemVariable,
                             boolean etsDelta)

Method Detail

increment

public void increment(double strataScore,
                      java.lang.String groupValue,
                      double itemScore)

Parameters:

strataScore - mathing score i.e. raw score, decile, or quintile

groupValue - examinees group membership

itemScore - examinees response to item

focalTotalSize

public double focalTotalSize()

cochranMantelHaenszel

public double cochranMantelHaenszel()

Returns:

Cochran-Mantel-Haenszel chi-square statistic

commonOddsRatio

public double commonOddsRatio()

Computed only for the first two rows and first two columns in each strata

Returns:

commonOddsRatioVariance

public double commonOddsRatioVariance()

commonOddsRatioConfidenceInterval

public double[] commonOddsRatioConfidenceInterval(double commonOddsRatio)

Computes 95% confidence interval for the common odds ratio. Used in computation of ETS DIF classification for binary items.

Parameters:

commonOddsRatio -

Returns:

smdConfidenceInterval

public double[] smdConfidenceInterval(double standardizedMeanDifference)

Computes 95% confidence interval for the standardized mean difference. Assumes SMD is distributed unit normal.

Parameters:

standardizedMeanDifference -

Returns:

varianceSMD

public double varianceSMD()

Compute variance of the standardized mean difference (SMD). This method is described in Zwick & Thayer (1996) Equation 7.

Returns:

etsDelta

public double etsDelta(double commonOddsRatio)

pF

public double pF()

Computes the standardized mean difference (SMD). For binary items, this method is the same as Dorans and Kulick (1986) STD P-DIF. See Zwick and Thayer (1996) for details.

Returns:

zSMD

public double zSMD()

Returns a Z test of the SMD statistic, Z_H(SMD) on page 194 of Zwick and Thayer (1996). This rho is distributed as a standard normal variate under the null hypothesis.

etsBinayClassification

public java.lang.String etsBinayClassification(double cochranMantelHaenszel,
                                               double pvalue,
                                               double commonOddsRatio)

smdDifClass

public java.lang.String smdDifClass()

getVariableName

public VariableName getVariableName()

getPValue

public double getPValue()

getSampleSize

public int getSampleSize()

getEffectSize

public double getEffectSize()

getEffectSizeConfidenceInterval

public double[] getEffectSizeConfidenceInterval()

getETSDifClassification

public java.lang.String getETSDifClassification()

printTables

public java.lang.String printTables()

From 1999 South Carolina PACT Technical Documentation

Returns:

printHeader

public java.lang.String printHeader()

getDatabaseString

public java.lang.String getDatabaseString()

This method provides the results in a form that can be inserted into a database table.

Returns:

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object